There are a number of applications in which it would be advantageous to be able to harness power, for hydroelectric power generation for example, from a flow of water having only a low head. A typical application is one in which power is to be generated by means of the water flow of a small river or stream where the head of water available is limited by the lie of the land and the necessity to limit civil engineering works on the basis of cost and/or environmental considerations. The use of conventional water turbines in such applications is for the most ruled out by the requirement for such turbines of high heads of water to obtain the necessary turbine speeds for economical generation of power. Other arrangements utilizing flapping gates, displaced floats and the like are ruled out because they are bulky and work with an intermittent action. Hydraulic rams are used extensively for raising water to provide a higher head, and a ram/turbine combination might be considered to provide a possible solution to this problem, although the size of ram required for the sort of flows envisaged in most applications would rule such an arrangement out in many circumstances.
It is an object of the invention to provide a new form of water turbine which is particularly suitable for use with a low head of water.